1. Field of the Invention:
This invention relates to the field of composite materials which are currently used in a very large number of industrial applications, i.e. in the field of materials comprising a polymer matrix including a reinforcement element.
The invention relates in particular to polyolefin matrix composites.
2. Description of the Prior Art:
In recent years, composite materials have undergone considerable development in all industrial fields, because the polymer matrices have--in addition to the ability to assume complex shapes--beneficial characteristics at a moderate cost, if their mechanical properties can be improved by the incorporation of a reinforcement material, either in the form of a mineral or organic additive (such as carbon black in elastomer matrices) or in the form of a--continuous or discontinuous --reinforcement comprising textile or metal threads or wires, or in the form of elastomer matrices (e.g. hoses or belts or tires), or thermosetting matrices (e.g. automobile suspension springs with an epoxy matrix, or high-technology composites for aerospace applications).
It is almost impossible--given the abundance of publications on the subject--to prepare a list of the prior art for elastomer matrix or thermosetting composites.
On the other hand, there are practically no references relative to polyolefin matrix composites, which is explained by the chemical nature of these materials, such as polyethylene, polypropylene or their semi-crystalline copolymers, which gives them high chemical inertness and, consequently, an absence of affinity for other materials, making adhesion substantially impossible between the polyolefin matrices and reinforcements other than polyolefins themselves (as illustrated in U.S. Pat. No. 4,501,856 of the Allied Corporation), without a chemical modification treatment--which is often very complex to perform--of the polyolefins, as described, for example, in U.S. Pat. No. 3,936,415 of Owens Corning Fiberglass Corporation, which uses an oxidized polyolefin.